Hydraulic safety system



' Sept. 26, 1967 Y s, JR I I 3,343,287

HYDRAULIC SAFETY SYSTEM Filed May 22, 1964 I 2 Sheets-Sheet 1 INVENTOR EDMUND J K/RAS JR BY AGENT Sept. 26, 1967 E. .1. KIRAS, JR 3,343,287

I HYDRAULIC SAFETY SYSTEM Filed May 22, 1,964 2 Sheets-Sheet 2 INVENTOR. EDMUND J. K/RAS JR.

AGENT.

United States Patent 3,343,287 HYDRAULIC SAFETY SYSTEM Edmund J. Kiras, Jr., Menlo Park, Calif. (128 N. 7th St., San Jose, Calif. 95112) Filed May 22, 1964, Ser. No. 369,521 4 Claims. (Cl. 37-129) The present invention relates to hydraulic safety systems and, more particularly, to a hydraulic safety system designed to prevent sudden falling of suspended loads upon the malfunction of the suspension system.

In our highly mechanized society, there are many instances when loads of one type or another must be suspended. And in many of these instances, failure of the suspension system can have serious consequences. Therefore, it is desirable to have suspension systems that are reliable. However, in some fields in which suspended loads play a part, it is not possible to have completely reliable suspension systems. One such field is the earth moving field.

One of the more common types of earth moving vehicle is known as a scraper. These scrapers comprise a scraper bowl suspended by a Wheeled frame pulled by a two or four wheel tractor. The scraper bowl may be raised or lowered with respect to the ground by the suspension system, e.g., cable or hydraulic, which is actuated by control mechanism on the tractor. The scraper bowl is conventionally provided with a cutting blade on its forward end which cuts into the ground when the bowl is in a lowered position. As the tractor pulls the scraper forward, earth is forced over the blade into the bowl. When the bowl is full, the suspension system is set into motion by the control means to raise the blade from the ground. The loaded earth, as much as thirty tons of it, may then be moved to the desired location. When moving the earth, the scraper is apt to reach speeds as high as fifty miles per hour. I

A cable or hydraulic line sometimes breaks or other types of failures of the suspension system occur. These failures are often the result of the great weight being supported and the rough terrain over which scrapers generally travel. As a result of such a failure, the bowl drops. Besides this alone being damaging to the scraper, if the scraper is moving, the bowl quickly cuts into the ground and causes the vehicle to suddenly stop. These stops, besides being detrimental to the equipment, can seriously injure the operator.

Thus it is apparent that it is of great importance to provide 'a means for preventing the bowl from dropping when the suspension system fails. While safety systems have previously been designed for this purpose, most of them only provide protection when the bowl is in a stationary position, e.g., raised for traveling. Even these systems have been complicated, subject to malfunction, and required frequent maintenance. In addition, most have required special manipulation by the operator. For the sake of speed, these devices are often ignored by the operator, often to his regret.

The present invention is a simple, relatively inexpensive system which provides the necessary safety without relying on the operator for its effectiveness. In general it comprises at least one hydraulic jack operatively connected between the bowl and the wheeled frame of the scraper. A fluid circuit provides communication between the chambers of the jack formed by the hydraulic piston therein for the purpose of allowing free movement of the piston, and thus also of the bowl. However, an unique valve in the fluid circuit instantaneously prevents fluid flow between the chambers, whenever the fluid flow pressure in the circuit signals a malfunction of the suspension system.

More particularly, this valve comprises a valve seat plate having at least one valve opening therein and a valve l of the fluid circuit and control gate adapted to seat within the opening upon fluid flow pressure in one direction through the opening, i.e., when the bowl is being lowered. Upon fluid flow pressure in the other direction through the opening, i.e., when the bowl is being raised, the valve is opened. There is also provided means for maintaining the valve gate open against the fluid flow pressure when the bowl is being intentionally lowered.

It is therefore an object of the present invention to provide an improved safety system for preventing sudden falling of suspended loads upon a malfunction of the suspension system.

Another object of this invention is to provide a simple hydraulic safety system for preventing the bowl of an earth moving scraper from falling upon a malfunction of its suspension system.

A further object of this invention is to provide a scraper bowl safety system that does not depend on the operator for its effectiveness.

A still further object of the present invention is to provide a hydraulic safety system for preventing the falling of the bowl of an earth moving scraper which is operative when the bowl is being raised as well as when it is stationary.

7 Other objects and advantages of the present invention will be apparent upon a consideration of the following description taken in conjunction with the attached drawings in which:

FIGURE 1 is a side elevation view of a conventional earth moving scraper and tractor unit with portions broken away to illustrate a preferred embodiment of the present invention;

FIGURE 2 is a top plan view of the forward end of the scraper and rear end of the tractor showing the present invention;

FIGURE 3 is a schematic, partly perspective, diagram mechanism of the present invention; and

FIGURE 4 is an alternative embodiment of a valve particularly adapted for the present invention.

In FIGURE 1, there is shown a earth moving vehicle 11 comprising a scraper 12 connected by draft member 13 to a rubber wheeled tractor 17. The main portion or bowl 16 of the scraper may be raised or lowered by pivoting about its connection to its wheels 17. The bowl is supported by a draft frame comprising spaced side arms 18 pivotally connected to the bowl by pins 19 and extending forward to a tubular cross member 21. The cross member 21 in turn is, rotatably connected to the draft member 13.

The bowl 16 of the scraper is provided with a scraping edge or blade 22 adapted to cut into the ground when the bowl is in a lowered position and fill the bowl as the scraper moves forward. An ejector 23 for discharging the contents of the bowl and an apron 24 for opening and closing the forward end of the bowl are also conventionally provided.

A conventional cable control unit 26 for raising and lowering the bowl takes power from a rear power takeoff shaft (not shown) of the tractor and includes a pair of cable winding drums, one of which, for raising and lowering the bowl, is indicated at 27. A cable 28- secured to and wound upon drum 27 leads from the drum over a cable-laying sheave 29, then around a guide sheave 31 and upwardly through the hollow center of the pivotal connection 32 of shaft member 13 to the tractor. From inside the connection 32, the cable passes over guide sheaves 33 and 35 and then through two groups of sheaves, one 34 carried on the cross member 21 and the other 36 on cross member 37 on the forward end of the scraper bowl. The end of the cable is suitably secured on the shaft member adjacent sheaves 34.

As can be seen, by taking in and paying out the cable on drum 27, the bowl may be raised or lowered respectively.

The operator conventionally operates the cable control unit by a hand lever 38 which coacts with an air, hydraulic or mechanical system to provide the necessary operation of the unit. The usual arrangement is such that when the hand lever occupies a neutral or mid position, it applies a suitable brake to the drum to prevent the drums rotation in either direction, thus keeping the bowl stationary. When the hand lever is rocked in one direction, e.g., toward the operator, it releases the brake and engages a suitable clutch to rotate the drum from the power take-off shaft to take in cable and thus raise the bowl. When the operator rocks the hand lever from the mid position in the opposite direction, it releases the brakes to permit free paying out of the cable and the lowering of the bowl.

In accordance with the invention and as shown both in FIGURES 1 and 2, two hydraulic jacks 39 and 41 are operatively connected between the bowl and the frame of the scraper. While two are shown, it is to be understood that any convenient number may be used. The cylinder ends of the jacks are pivotally connected to the rearward side of the tubular cross member 21 while the piston ends of the jacks are pivotally connected to bowl cross members 37, one on each side of the sheaves 36.

A hydraulic fluid circuit communicates the two chambers formed within each jack by the iston therein in order to allow free movement of the piston. This, in turn, assures that the jacks will not interfere with the normal operation of the bowl. The fluid circuit comprises in part hydraulic hoses 42 and 43 connected to the jacks 39 and 41, respectively, very near their top, and also to a T joint 44 on a supply tank 46. Hose 47 leads from the supply tank to one end of valve 48 to be more fully described infra. Another hose 45 leads from the other end of valve 48 to a T joint 50 on the scraper end of shaft member 13. Hoses 49 and 51 lead from this T joint to the piston ends of jacks 39 and 41 respectively. Thus it can be seen that when valve 48 is open, as is the case except when there is a malfunction, free fluid communication is provided from the upper or cylinder chamber of each jack to the lower or piston chamber, i.e., from the cylinder chamber through supply tank 46 to valve 48 and then to the piston chamber of each jack.

As mentioned before, valve 48 is designed to be open for normal operation, but to automatically close if the suspension system malfunctions. As shown in cross-section in FIGURE 3, valve 48 comprises a housing 52 divided into two chambers 53 and 54 by a valve seat plate 56. A valve member 57 having a gate 58 within chamber 53 is adapted to seat within and block opening 59 in the plate 56. The gate 58 has a rod 61 rigidly attached thereto and extending through opening 59 and through a guide 62 in the housing. Suitable sealing means, such as rings 63 are provided between valve rod 61 and guide 62 to prevent leakage of hydraulic fluid therebetween. One end of a spring 64 is attached to a collar 66 on valve rod 61 and the other end is attached to the guide 62. This spring is in slight tension, thereby always tending to seat the gate 58. Therefore, any time the system is relatively motionless, e.g., when the scraper is traveling, the valve is closed. If a malfunction should occur at this time, the valve is already closed and no downward motion of the scraper bowl whatsoever is allowed.

Hydraulic hose which conducts fluid to and from the piston chambers of the jacks, is connected to chamber 53 over the gate 58 such that hydraulic fluid flowing from this hose will bear upon the gate. Hose 47 which conducts fluid to and from the cylinder chambers of the jacks through tank 46 is connected to valve chamber 54 at any convenient location.

As is apparent, hydraulic fluid may flow easily from chamber 54 to chamber 53 through opening 59 by forcing gate 58 to an open position. Thus, whenever, the bowl is moved upward, the valve is no obstacle to communication between the cylinder and piston chambers of the jacks. However, it is also seen that due to the placement of hose 45, fluid flowing into chamber 53 will normally close gate 58' and thus prevent flow from chamber 53 to chamber 54 and thus prevent lowering of the bowl. Therefore, to allow the bowl to be purposefully lowered, means are shown in FIGURE 3 coa'cting with the suspension system hand lever 38 to hold the valve 48 open at such time. Specifically, when hand lever 38 is rocked away from the operator (to the left) to release the brake on drum 37, it rotates rod 67. Rotation of rod 67 pivots lever system 68 which in turn rotates rod 6'9 in the direction indicated by the arrow. As shown, a lever 71 is rigidly connected to rod 69 and is situated to bear upon valve rod 61 whenever rod 69 rotates to the left in response to the movement of the hand lever. Thus, whenever the hand lever is actuated to lower the bowl, the valve 48 is held open. But if the bowl should begin to drop without actuation by the hand lever, fluid flow from hose 45 coupled with the slight tension on spring 64 will close the valve and prevent the bowl from lowering. It should be noted that if there is a malfunction and it is thereafter desired to lower the bowl, this may be easily accomplished by actuating hand lever 33 away from the operator to open the valve 48 a small amount.

Lever 71 should be a suflicient distance from valve rod 61 whenever the hand lever is in a neutral position as shown to allow unobstructed closing of the valve. When the bowl is being raised, lever 71 is pivoted away from the valve rod and will not hinder the valve if a malfunction occurs at such time.

It is to be understood that depending on the particular scraper any appropriate linkage system may be used to translate the motion of the hand lever to prevent valve 48 from closing during an intentional lowering of the bowl. For example, if it was desired, valve 48 may even be placed below the hand lever with valve rod 61 in contiguous relationship to spur 72. Then upon actuation of the hand lever to the lower position, it would hold the valve open directly. The earlier described linkage, in fact, is the standard linkage on one type of scraper for controlling the motion of the drum. Rod 73, partly shown, releases the brake and engages the drum clutch, or just releases the brake depending on its direction of movement.

Another embodiment of the valve adapted for safety systems requiring a high fluid flow rate is shown in FIG- URE 4. Two valve gates 76 and 77 and two corresponding valve openings 78 and 79 are provided in valve seat plate 81. The hydraulic hoses from the piston chambers of the jacks lead into a manifold 82. Fluid flowing from this manifold through inlets 83 and 84 infringes on both the valve gates 76 and 77.

A bearer arm 86 adapted to contact both of the valve rods 87 and 88 is pivotally connected to lever 89. While the bearer arm is not necessary, due to the fact it is pivotal it is preferred in order to hold both valve gates open the same amount. In all other respects, this valve is similar to the earlier described valve.

It can readily be seen that the present invention has many advantages besides those noted supra. For example, it is apparent that the only time a load is placed on the safety system is when a malfunction of the suspension system does occur. In addition, it has few moving parts. This ensures a long life and reliability.

If the suspension system of the scraper is hydraulic, the valve of the present invention alone with appropriate linkage to the hand lever may be used. Then the driving jacks take the place of jacks 39 and 41, and the valve is inserted into the hydraulic driving circuit. However, such a system would not give complete safety. If the hydraulic line between the bowl end of the driving jacks and the valve should break, the valve would not prevent the bowl from falling. Therefore, if the valve is so used in a hydraulic driving system, it is desirous that the hose between it and the lower end of the driving jacks be short and stronger than the other hoses to reduce the probability of it being the one to break.

The above and other modifications within the skill of the art are meant to be included within the scope of the invention. Therefore, it is intended that only the following claims be considered as limiting the invention.

What is claimed is:

1. A hydraulic safety system for a load suspension system which includes means for raising and lowering the load and a control means for actuating said raising and lowering means, said safety system preventing sudden falling of suspended loads upon a malfunction of the suspension system and comprising at least one hydraulic jack operatively connected between the suspended load and the suspending frame, a single fluid circuit solely communicating the chambers of said jack formed by the hydraulic piston therein, a hydraulic valve within said fluid circuit, said valve comprising a valve seat plate having at least one valve opening therein, a valve gate adapted to seat within said opening upon fluid flow pressure through said opening from the jack chamber at the end of said jack connected to said load to close said valve and prevent fluid flow between said jack chambers, and to open upon fluid flow pressure in the other direction through said opening, and means coacting with said suspension system control means for automatically maintaining said valve gate in the open position against said fluid flow pressure from the jack chamber at the end of said jack connected to said load at all times said control means is in the load lowering mode.

2. In combination with an earth moving scraper and tractor unit having means for raising and lowering the bowl of said scraper and control means for actuating said raising and lowering means, a hydraulic safety system for preventing falling of said bowl on the failure of said raising and lowering means comprising at least one hydraulic jack operatively connected between said bowl and the frame of said scraper, a single fluid circuit solely communicating the chambers of said jack formed by the hydraulic piston therein, and a valve in said single circuit responsive to fluid pressure in said circuit from the jack chamber at the end of said jack connected to said bowl for closing said single circuit to prevent fluid flow between said chambers, and means coacting with said control means for automatically rendering said valve open at all times said control means is in the bowl lowering mode.

3. In combination with an earth moving scraper and tractor unit having means for raising and lowering the bowl of said scraper and control means for actuating said raising and lowering means, a hydraulic safety system for preventing falling of said bowl on the failure of said means comprising at least one hydraulic jack operatively connected between the forward end of said bowl and the frame of said scraper, a single fluid circuit solely communicating the chambers of said jack formed by the hydraulic piston therein, a valve in said circuit comprising a valve seat plate having at least one valve opening therein, a valve gate adapted to seat within said opening upon fluid flow pressure through said opening from the jack chamber at the end of said jack connected to said bowl to close said valve and prevent fluid flow between said jack chambers, and to open upon fluid flow pressure in the other direction through said opening, and means coacting with said control means for automatically maintaining said valve gate in the open position at all times said control means is in the bowl lowering mode.

4. In combination with an earth moving scraper and tractor unit having means for raising and lowering the bowl of said scraper and a hand lever for actuating said raising and lowering means, a hydraulic safety system for preventing falling of said bowl on the failure of said raising and lowering means comprising at least one hydraulic jack operatively connected between the forward end of said bowl and the frame of said scraper, a single fluid circuit solely communicating the chambers of said jack formed by the hydraulic piston therein, and a hydraulic valve in said circuit, said valve comprising a housing having first and second chambers separated by a valve seat plate, said valve seat plate having at least one valve opening providing communication between said chambers, a valve gate within said first chamber adapted to seat within said opening upon fluid flow pressure from the first of said chambers to the second to close said valve and prevent fluid flow between said chambers, and to open upon fluid flow pressure from said second chamber to the first,

said valve being connected into said circuit with said first chamber being in communication with the jack chamber at the end of said jack connected to said bowl, and with said second chamber in communication with the other jack chamber, a rod rigidly connected to said valve gate and extending through said opening and second chamber to the exterior of said housing, and means coacting with said hand lever for automatically bearing against said rod to prevent said valve gate from seating within said opening at all times said hand lever is in the bowl lowering mode.

References Cited UNITED STATES PATENTS 869,323 10/1907 Nolan 137-541 2,206,425 7/1940 Perman 137541 X 2,897,613 8/1959 Davidson et al. 37-426 ABRAHAM G. STONE, Primary Examiner. WILLIAM A. SMITH III, Examiner.

A. E. KOPECKI, Assistant Examiner. 

1. A HYDRAULIC SAFETY SYSTEM FOR A LOAD SUSPENSION SYSTEM WHICH INCLUDES MEANS FOR RAISING AND LOWERING THE LOAD AND A CONTROL MEANS FOR ACTUATING SAID RAISING AND LOWERING MEANS, SAID SAFETY SYSTEM PREVENTING SUDDEN FALLING OF SUSPENDED LOADS UPON A MALFUNCTION OF THE SUSPENSION SYSTEM AND COMPRISING AT LEAST ONE HYDRAULIC JACK OPERATIVELY CONNECTED BETWEEN THE SUSPENDED LOAD AND THE SUSPENDING FRAME, A SINGLE FLUID CIRCUIT SOLELY COMMUNICATING THE CHAMBERS OF SAID JACK FORMED BY THE HYDRAULIC PISTON THEREIN, A HYDRAULIC VALVE WITHIN SAID FLUID CIRCUIT, SAID VALVE COMPRISING A VALVE SEAT PLATE HAVING AT LEAST ONE VALVE OPENING THEREIN, A VALVE GATE ADAPTED TO SEAT WITHIN SAID OPENING UPON FLUID FLOW PRESSURE THROUGH SAID OPENING FROM THE JACK CHAMBER AT THE END 